Downloadable Sounds

None of us want our hardware to become obsolete. So what do you do when you've tired of your sound card's ROM presets or you can't stomach another General
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None of us want our hardware to become obsolete. So what do you do when you've tired of your sound card's ROM presets or you can't stomach another General MIDI violin? You might find the answer in downloadable sounds. These give you access to hundreds or even thousands of new sounds that you can use in your sound card, in a hardware sampler, or even in a software sampler running on your computer. Unlike with most sound-card presets, you can tweak, twist, and fine-tune downloadable sounds to your liking.

Here, we'll discuss SoundFont and DLS, the two most common formats for downloadable sound, as well as third-party editors and libraries for creating your own sounds. We'll also cover some of the hardware and software supporting these formats and explore their use in your music productions.

THE SOUNDFONT SPECS
SoundFont is a downloadable-sound format designed by Creative Labs. Originally limited in their specifications and use, today SoundFont files can sound great, and a number of Windows and Mac audio programs support them. SoundFonts consist of Presets (similar to Roland Patches or Kurzweil Programs) that are assigned MIDI Program Change numbers with which you can select them. Presets are made from Instruments, which contain voicing data (more on this later) and keymap information that links samples to specific notes on the keyboard. The keymap consists of samples drawn from a collection called the Sample Pool.

SoundFonts typically have an SF2 file extension. The format combines two types of data: the first is the sampled audio data itself, typically originating as a WAV file, and the second is the synthesis information required to articulate or modulate the digital audio, sometimes referred to as the voicing data. When you strike a note on the keyboard, a MIDI Note On message goes to the SoundFont synthesizer, which tells it the corresponding sound to play (sampled audio data) and how to respond over time (voicing data).

The sampled-audio specification calls for standard 16-bit samples with a variable sampling frequency of up to 48 kHz. Samples use a standard looping scheme comprising parameters for Sample Start, Sustain Loop Start, Sustain Loop End, and Sample End. Other parameters include Original Key, which defines the MIDI key number that the original sample corresponds to, and Pitch Correction, which allows a tuning adjustment of plus/minus100 cents.

The voicing data falls into two distinct categories as well, function blocks and function modulators. Function blocks are the characteristics of the sound that you can control-frequency, pitch, and amplitude. Function modulators are the parameters that affect these three characteristics. Modulators can consist of internal sources such as low frequency oscillators (LFOs) or envelope generators (EGs); physical sources such as the modulation or pitch-bend wheels; or MIDI control sources such as MIDI Controllers 91 and 93 (Reverb Depth and Chorus Depth). The modular design provides a great deal of flexibility-you can route any modulation source to any modulation function, resulting in greater sonic variety.

SoundFont internal modulators consist of two EGs, one tied to amplitude and one available for pitch or filter modulation. Each EG allows for standard Attack Rate, Decay Rate, Sustain Level, and Release Rate, plus a Delay Rate segment prior to the Attack Rate and a Hold Rate segment between the Attack and Decay segments. Two LFOs are available to modulate frequency, pitch, or amplitude. Each LFO consists of a Frequency Rate that determines the speed of the oscillator and a Delay Rate that controls the time until the LFO starts its modulation.

A SoundFont can also include a filter, typically a second-order (2-pole) filter with resonance. Its frequency range is 0 Hz to 20 kHz. As previously mentioned, SoundFont effects include Reverb Depth and Chorus Depth, which respond to MIDI Controllers 91 and 93, respectively. Because the synthesizer generates the effects themselves, the quality varies from device to device.

DLS LEVEL 1 AND DLS LEVEL 2
DLS stands for Downloadable Sounds. Like SoundFont, DLS is a sound-file format. The two current versions of the DLS standard are known as DLS Level 1 and DLS Level 2. The MIDI Manufacturers Association (MMA) developed both in collaboration with members of the Interactive Audio Special Interest Group. For detailed specifications on the DLS Level 1 format, see "Desktop Musician: Down and Out in Cyberspace" in the December 1998 issue of EM, or visit the MMA's Web site at www.midi.org. The following passages provide a brief overview of the DLS structure as well as a description of the additions featured in DLS Level 2.

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FIG. 1: The main editing page in Creative Labs'' SoundFont editor Vienna provides numerous parameters for tweaking SoundFonts. Anyone who has ever used a patch editor should find the interface familiar.

DLS files consist of Instruments, Regions, Articulations, and the samples themselves. Instruments-equivalent to SoundFont Presets-have assigned names and MIDI Program Change numbers for easy access. Two types of Instruments are available: Melodic Instruments, which contain up to 16 Regions, and Drum Instruments, which contain up to 128 Regions. A Region includes keymapping information and a reference to the audio sample to play. Regions also contain the synthesis, or voicing, parameters-DLS calls them Articulations-such as EGs and LFOs. DLS Level 1 Articulation parameters consist of two Envelope Generators, one for pitch and one for amplitude, as well as one LFO for modulating pitch or amplitude. Melodic Instruments can contain one Articulation for all Regions, whereas Drum Instruments can have a separate Articulation for each region. DLS samples can consist of 8- or 16-bit sample data and contain pitch, volume, and root-key information.

DLS Level 2 provides increased functionality to the DLS Level 1 specification. Additions include a 2-pole filter with resonance, a second LFO, layering of Regions, 6-stage Envelopes, per-Region Articulations on Melodic Instruments, and standardized responses to MIDI controllers. DLS Level 2 also includes a standardized method of adding extra synthesis capabilities for developers who want more features.

SOUND RESOURCES
You can choose among several different sound editors for making your own downloadable sounds. Creative Labs includes Vienna, a popular SoundFont editor, free with its SoundFont-compatible cards (see Fig. 1); you can also download Vienna from the Web at www.creativelabs.com. Another popular editor is Awave ($55) by FMJ-Software (www.fmjsoft.com). This general-purpose sound editor supports multiple file formats, including SoundFont, DLS Level 1, and DLS Level 2. Audio Compositor ($40), another shareware editor, supports SoundFont and both levels of DLS; you can find it at http://home.att.net/~audiocompositor. Megota Software offers a SoundFont patch manager called AweVBank 98 as well as a SoundFont compression program called SFPack, both available at www.megota.com.

Steinberg's ReCycle 1.7 allows you to dissect audio files into samples and MIDI events, and it has editing features similar to those of Vienna. You can get more information at www.us.steinberg .net. Finally, Microsoft's Synth Author and DirectMusic Producer are free DLS Level 1 editors available at www.microsoft.com. (DirectMusic 8.0, which Microsoft will release this spring, allows DLS Level 2 editing and auditioning.)

The number of hardware and software synthesizers that support SoundFonts and DLS is rapidly growing, no doubt due to the synthesis power that they can generate at such an attractive price. Some of the more popular sound card-based synthesizers supporting SoundFonts are the Creative Labs Live card, the E-mu Audio Production Studio (APS), and the EWS64 line of TerraTec cards (very popular in Europe). These cards have much higher specs than the older models do and often include studio-quality A/D/A converters, balanced analog I/O, S/PDIF I/O, and high-quality stereo and surround-sound effects. For DLS-supported sound cards, check out the Turtle Beach Montego II, the Yamaha 192XG, and the TerraTec line.

Software-based synths and samplers are convenient because they interface with whatever audio output device you have on your computer without requiring additional hardware. Seer Systems (www.seersystems.com) makes two such Windows products: Reality ($379), a full-featured synthesizer with sampling options that supports SoundFonts; and SurReal ($99), a lower-cost, scaled-back version of Reality. Unity DS-1 ($449) from BitHeadz (www.bitheadz.com) is another SoundFont-compatible software sampler that runs on Macs and PCs, and NemeSys (www.nemesysmusic.com) has announced that its new GigaStudio software sampler will support SoundFonts as well. DLS software synths include MIDI Wave Lite ($49) by Galileo Designs (www.galileodesigns.com) and Microsoft's DirectMusic synthesizer, a component of DirectX 6.1 (built into newer Windows operating systems).

Downloadable sounds can also be used in your external hardware sampler. With a converter such as ChickenSystems' Translator (www .chickensys.com), you can convert a SoundFont to a format that Kurzweil, Ensoniq, Akai, Roland, and other samplers are able to read. You can also convert sounds from those hardware formats to SoundFonts and perform other types of conversions.

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FIG. 2: SoundFont support is beginning to show up in modern sequencers. Here, the SoundFont bank manager appears inside Cakewalk''s Pro Audio.

Using SoundFonts in a recording situation has become easy with SoundFont support from both Cakewalk's Pro Audio and Steinberg's Cubase digital audio sequencers. If your sound card is SoundFont-compatible, you simply load a SoundFont bank directly from your sequencer and select your SoundFont instrument in the Track window (see Fig. 2). The process couldn't be easier. Of course, you can play a sound-card synth loaded with downloadable sounds using any sequencer, but not all sequencers support the format as directly as these two.

SoundFont libraries are proliferating as the format gains popularity. Among the many current producers of SoundFonts are Creative Labs, E-mu/Ensoniq (www.emu.com), and SonidoMedia (www.sonidomedia.com). You can also find free SoundFonts on the Web, but their quality is not always guaranteed. Most of the companies mentioned here include product demos on their Web sites so that you can hear what you're getting before you buy.

DLS sound libraries are more difficult to find, but programs such as Awave and Audio Compositor allow you to open a SoundFont and save it as a DLS Level 1 or DLS Level 2 file. Be aware, however, that when you convert from a SoundFont to a DLS Level 1 file, you lose any filtering or layering programmed into the SoundFont patch.

SOUNDFONTS AND DLS FILES
Creating music using SoundFonts and DLS is just like creating music with any type of sound hardware: all you really need is a MIDI controller or a sequencer and the hardware (or software sampler) that plays the selected sounds. Although you can use any sequencer, you'll probably find the task to be faster and easier with a program that can address the sound banks internally.

How you load SoundFonts or DLS sounds depends on the hardware or the software sampler you're working with. Some sound cards have factory-or user-installed RAM into which you can load your sounds, but most use your computer's RAM to store the sample data when you access it. The more system RAM you have, the more downloadable sounds you can load at one time. When you're not sampling, the system RAM is available for other applications. (Some cards load sounds into RAM at startup. Check with the manufacturer to see which method your card uses.)

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FIG. 3: Most sound cards are bundled with software for managing downloadable sounds. The E-mu APS SoundFont Bank Manager, shown here, lets you select a sound bank and preview the ­Presets that it contains.

In Fig. 3, we see the screen from which you select the SoundFont file that loads into the E-mu APS card when you start your computer. Simply click the Browse button to locate all of the sounds on your system, then choose the one that you want. You can preview the sounds in the bank using the onscreen keyboard and modify other card settings as well. Loading downloadable sounds is relatively simple; the product manual should explain it all.

FONT OF WISDOM
As the industry takes hold of downloadable formats, we will see them become even better integrated with audio software. Some of the leading MIDI sequencer developers are already working toward routing plug-in effects onto SoundFont and DLS tracks. Keyboard synth manufacturers are discussing direct support for these formats because of their growing popularity and available libraries. If you're seeking new sonic resources for your music productions, be sure to check out downloadable sounds.

Jennifer Hruska is president of Sonic Network, a network of PC-audio Web sites, including Sonic Implants, the maker of downloadable SoundFont, DLS, Akai, and Kurzweil sound libraries. You can hear her work at www.sonicimplants.com.